Gow S M, Kellett H A, Seth J, Sweeting V M, Toft A D, Beckett G J
Clin Chim Acta. 1985 Nov 15;152(3):325-33. doi: 10.1016/0009-8981(85)90108-1.
Sensitive immunoradiometric assays (IRMA) for TSH and radioimmunoassay (RIA) kits for free thyroid hormones (fT4, fT3) are becoming increasingly used for routine thyroid investigations. We have assessed these tests in 93 euthyroid pregnant women. Mean fT4 and fT3 values decreased with gestation by 24-27% and 14-35%, respectively, using several analogue RIA kits. Some patients had free hormone values which fell below the reference range derived from non-pregnant euthyroid patients. By contrast, the fT4 concentrations measured by direct equilibrium dialysis fell by only 16% with all values within the reference range. Serum non-esterified fatty acid (NEFA) levels (non-fasting) did not correlate with fT4 and fT3 but a spurious effect of serum albumin levels on the free hormone kits was suggested. TSH results showed that the majority of subjects had lower values measured by IRMA than by RIA. Three patients had basal TSH (IRMA) below the mean detection limit of the assay; this could have been falsely interpreted as indicating hyperthyroidism. We conclude that, as with longer established thyroid function tests, special care must be taken in interpreting results of these new thyroid function tests in pregnancy.
用于促甲状腺激素（TSH）的灵敏免疫放射分析（IRMA）和用于游离甲状腺激素（fT4、fT3）的放射免疫分析（RIA）试剂盒越来越多地用于常规甲状腺检查。我们对93例甲状腺功能正常的孕妇进行了这些检测评估。使用几种类似的RIA试剂盒，fT4和fT3的平均水平分别随孕周下降了24% - 27%和14% - 35%。一些患者的游离激素值低于非妊娠甲状腺功能正常患者得出的参考范围。相比之下，通过直接平衡透析测得的fT4浓度仅下降了16%，所有值均在参考范围内。血清非酯化脂肪酸（NEFA）水平（非空腹）与fT4和fT3无关，但提示血清白蛋白水平对游离激素试剂盒有假性影响。TSH检测结果显示，大多数受试者通过IRMA测得的值低于RIA测得的值。三名患者的基础TSH（IRMA）低于该检测的平均检测限；这可能被错误地解释为甲状腺功能亢进。我们得出结论，与已确立较长时间的甲状腺功能检测一样，在解释这些新的孕期甲状腺功能检测结果时必须格外小心。
